1. Field of the invention
The present invention relates to a new process of the cantilever structure in the micro-electro-mechanical system (MEMS), and more particularly, to a process that overcomes the contamination problem on the undesired areas during the thin-film growth. Their advantages include not only to substitute the complex technique with sacrificial layer, but also to increase the yield for its simple structure and to deal the sub-micron microelectromechanical system technology for the mature stage on the wet-etching skill.
2. Description Of The Prior Art
The application of metal deposition commonly includes sputtering deposition and evaporating deposition. For the VLSI processing, how to boost the continuous developing of ladder layer and filling, especially to avoid the contaminated and destructive problems on the undesired areas during sputtering deposition will be one of major objectives today.
There are two conventional methods (as shown in FIG. 1) for the post-processing to deposit metal thin-film or oxide layer on the cantilever structures of the microelectromechanical system. The first is sacrificial layer technology as shown in FIG. 1 (A) which is made by the silicon oxide thin-film as a mask to isolate the specific deposition area, said mask isolates the area of metal thin-film 12 (PbTiO3) and 13(Bi) on the sacrificial layer 11 in MEMS 10, after the complete of sputtering deposition or evaporating deposition, finally, delete the sacrificial layer by etching skill. Another is destructive growth technology as shown in FIG. 1(B) which is to deposit metal thin-film 22(PbTiO3) and 23(Bi) on MEMS 20, then etching the undesired area separately into device size and its shape.
Those two conventional methods with drawbacks that not only increasing the mask number that easy to have the contamination problem on the undesired areas during sputtering deposition and decrease its dc signal sensitivity and ac signal response time, but also result destructive problems on the undesired area due to its complexity; besides, the main sensor section cannot be made into array repeatedly that cannot boost its sense performance also not easy to decrease its die size totally, therefore decreasing the operation speed and increasing power consumption.
Except for increasing the complexity or difficulty on the process, these two conventional methods own the result contaminated and destructive problems on the undesired areas for decreasing the operation speed and lifetime of electronic devices. Thus, at the same study for the MEMS, how to overcome these problems will be one of major objectives today.